Some physicochemical and microscopic characteristics of Greek unifloral honeys A Thrasyvoulou, J Manikis To cite this version: A Thrasyvoulou, J Manikis. Some physicochemical and microscopic characteristics of Greek unifloral honeys. Apidologie, Springer Verlag, 1995, 26 (6), pp.441-452. hal-00891310 HAL Id: hal-00891310 https://hal.archives-ouvertes.fr/hal-00891310 Submitted on 1 Jan 1995 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Review article Some physicochemical and microscopic characteristics of Greek unifloral honeys A Thrasyvoulou J Manikis 1 Laboratory of Apiculture-Sericulture, Aristotle University of Thessaloniki, 54006 Thessaloniki; 2 Union of Beekeeping Associations of Northern Greece, Prometheus 6, 55134 Kalamaria, Greece (Received 20 February 1995; accepted 16 May 1995) Summary — Water content, ash, HMF, diastase activity, electrical conductivity, pH, proline and micro- scopic characteristics of 174 samples of unifloral honeys from thyme, chestnut, cotton, heather, orange, sunflower, pine and fir honeydew have been analysed. Differences among the corresponding values are given. The honeys from pine, fir, chestnut and heather have a high pH, electrical conductivity and ash, but a low HMF. Thyme honey has high diastase and proline content where as orange honey shows the lowest values for pH, proline, diastase activity, ash and electrical conductivity. Sunflower and cotton honeys have no distinct characteristics. Predominant pollen was found in thyme, sunflower, heather and chestnut honeys. More than 20 pollen types were found in pine and thyme honeys, 15-20 in fir, sunflower and heather and 10-15 in chestnut, cotton and orange honeys. honey / unifloral / physicochemical characteristics / microscopic characteristics / Greece INTRODUCTION fir honey, which represents 5% of the total annual production. It is derived from honey- The annual honey production of Greece is dew produced by the insects Physokermes estimated at 11 000 tons. A large portion is hemicryphus, Eulecanium sericeum and derived from honeydews from pine and fir Mindarus abietinus, parasites on Abies trees (Santas and Bikos, 1979). cephalonica Loudon and A borisiiregis Mattf, Pine honey constitutes about 60% of the (Santas, 1983). total annual honey production and is pro- The large variety of melliferous sources duced during autumn from honeydew also enables Greece to produce character- secreted by the insect Marchalina hellenica istic unifloral nectar honeys. The most well- (Gennadius), which is restricted to Pinus known is ’Hymettus honey’, which has been brutia Ten and P halepensis Miller (Boden- famous since antiquity (Crane, 1979). This heimer, 1953; Nikolopoulos, 1959; Kailidis, is a thyme honey which is mainly produced 1965). Another major honeydew honey is from Thymus capitatus L, T serpyllum L and Satureia spp. Thyme honey represents 10% their organoleptic, microscopic and physico- that were of the total crop (Santas and Bikos, 1979). chemical characteristics. Samples doubtful in origin were excluded from the study. Heather, sunflower, orange and cotton hon- All samples were kept in a refrigerator until chem- are also Greek unifloral eys major honeys ical analysis. that are produced in appreciable quantities which have not yet been estimated. Heather honey is produced mainly from Erica verti- Physicochemical analyses cillata Forskal and E carnea L during autumn. While sunflower honey from Water content, ash, HMF and diastase Helianthus annuus L is significant, it is pro- activity were measured as recommended the Codex duced in because of by decreasing quantities Alimentarius Commission (CAC, 1989). the small monetary rewards associated with The electrical was measured it. Cotton (Gossypium hirsutum L) and conductivity according to Louveaux et al (1973). The results on the other orange (Citrus spp) honeys, are expressed in millisiemens/cm. The pH was hand, usually appear on the Greek market measured in a 20% solution. Proline was esti- mixed with other blossom honeys. Finally, mated by using the method of Ough (1969) at chestnut honey, which is produced from the 520 nm, with the aid of a calibration curve nectar of Castanea sativa Mill, may be partly obtained from solutions of pure dry proline. Ten of honeydew origin because of the honey- samples of each category of honey were anal- for content. dew that is abundantly produced by the ysed proline insect Myzocallis castanicola Baker (San- tas, 1983). Melissopalynological analysis The physicochemical characteristics of Greek unifloral honeys were partly exam- ined by Kodounis (1962), Thrasyvoulou and Melissopalynological analysis was carried out using the methods established by the Interna- Bladenopoulou (1984), Thrasyvoulou tional Commission of Bee Botany described by Bakandritsos and (1986), et al (1993) Louveaux et al (1978). Counts were expressed as Thrasyvoulou and Manikis (1993). Most of percentages after counting > 600 pollen grains. the published material appears in Greek The ratio of honeydew elements to the number of journals and is not easily accessible to the pollen grains (HDE/P) was estimated in honeydew international scientific community. In this honeys by counting fungal spores, hyphae, algae and 300 The fre- paper, we examine some characteristics of approximately pollen grains. classes of were as the Greek nectar to further quency pollen grains given major honeys predominant pollen (> 45%), secondary pollen contribute to the classification and charac- (16-45%), important minor pollen (3-15%) and terization of European unifloral honeys. minor pollen (1-3%.). MATERIALS AND METHODS RESULTS AND DISCUSSION Sampling Physicochemical characteristics Fresh samples of pine, fir, chestnut, thyme, sun- Table I shows the mean results and basic heather and flower, cotton, orange honeys pro- statistics obtained from the physicochemical duced in different regions of Greece were col- lected from beekeepers between 1989 and 1993. analyses, the percentage of the main pollen Their classification as unifloral honey was based in the unifloral honeys and the HDE/P ratio on their origin (information from beekeepers) and in the honeydew honeys. Water content Electrical conductivity The majority of Greek honey was found to Honeydew and chestnut honeys had the be low in moisture and therefore virtually highest conductivity while orange honey had safe from fermentation. Average moisture the lowest. Sunflower and thyme honeys content (16.8%) was 4.2% lower than the gave similar values; the same was found maximum allowable content for honey by for heather and cotton honeys. the CAC The values were (1989). greatest The high mean and wide range of elec- also lower than the maximum permissible trical conductivity of chestnut honeys level of 21 % with the of 2 sam- exception are noteworthy. Similar results were reported ples of heather honey. Fir honey had the by Piazza et al (1986, 1991) who showed lowest moisture content (15.2%) and that nectar chestnut had honeydew- heather the highest (18.6%). like characteristics (high pH, ash and con- The average moisture content of Greek ductivity) but differed from honeydew hon- fir, thyme, heather, sunflower, chestnut and eys by its negative specific rotatory value. orange honeys (16.8%) was lower than the The conductivity of Greek heather honey corresponding value for Italian (17.3%; agrees with that of the French (Pourtallier Accorti et al, 1986) and French (17.6%; and Taliercio, 1970), Italian (Persano Oddo Pourtallier and Taliercio, 1970) honeys. The et al, 1988) and Spanish (Serra Bonvehi distinct low water content of fir honey is in and Granados Tarres,1993) heather hon- agreement with Accorti et al (1986). eys. The high water content for heather agrees with values reported in other coun- tries (Spettoli et al, 1982; Accorti et al, 1986; Ash Serra Bonvehi and Granados Tarres, 1993). Since the of heather have majority honeys The highest ash content was found in hon- high water content, the specification of Cal- eydew and chestnut honeys and the low- luna in the standards for compositional est in orange nectar honey. Two samples honey is not considered as necessary. of fir honey (12.5%) and all the chestnut honeys exceeded the maximum tolerance of the CAC standard. Such high ash content pH indicates an increased nutritional value of honey rather than adulteration (Feinberg, Honey from orange trees had the lowest 1951). pH, whereas pine, fir and chestnut honeys The high values of pH, ash, and electri- had the highest. Heather honey gave an cal conductivity of Greek honeydew hon- average pH, value of 4.2, placing it between eys are similar to data given for the average flower honeys and honeydew. composition of honeydews from other coun- The pH values of Greek unifloral hon- tries (Kirkwood et al, 1960; White et al, eys are in agreement with those found by 1962; Stefanini, 1984; Talpay, 1985; Accorti Pourtallier and Taliercio (1970), Accorti et al et al, 1986). These features can be used (1986), Sabatier (1988), and Serra Bon- to distinguish between honeydew and